The primary objective of this career development award is to prepare the candidate to perform quantitative research as an independent investigator in the field of aging, specifically in the area of balance disorders of older adults. The candidate has backgrounds in mechanical and biomedical engineering and physical therapy. Consequently he has positioned himself to understand the problems of clinical populations and apply analytical techniques to study these problems in a quantitative fashion. The candidate intends to use this award to receive focused coursework and research training related to aging populations. The candidate intends to augment his education in the engineering and clinical sciences with coursework in two core areas: 1) aging and neurophysiology, 2) ethical training. Dr. Mark Redfern and Dr. Joseph Furman, two highly respected researchers, will mentor the candidate's research development. With their guidance, the candidate will receive intensive training in postural control research methods in the study of older adults and persons with vestibular disorders. The primary objective of this research is to increase our understanding of the combined effects of aging and vestibular disease on postural control in an effort to reduce the risk of falling in older adults. Patients with vestibular dysfunction commonly report a feeling of imbalance in situations with complex and rapidly changing visual stimuli such as in supermarkets. It is possible that reduced sensory function in older adults, or a slowing in central processing, may render the central integration of such information more difficult, resulting in greater imbalance. The proposed research will examine the postural sway response of older and younger adults, with and without vestibular disorders, as they view a moving visual scene. The first experiment will investigate the steady- state postural sway response to a scene that moves in a predictable manner for 60 seconds. The second experiment will examine the transient sway response to a scene that changes every 20 seconds. We hypothesize that the combined effects of aging and vestibular disease will result in greater postural sway during steady-state conditions, and that an inappropriate postural response will persist after the visual stimulus changes during transient conditions. Data obtained from these experiments will be used to validate feedback models of postural control. Understanding how older subjects with vestibular disorders integrate sensory information during these conditions will enhance our ability to develop balance rehabilitation programs in an effort to reduce the risk of falls in older adults.